Watches. A lot people used to wear them, because a watch had two great functional purposes: giving you the current time instantly, and providing a quick, easy, and almost universally recognized way to socially cue that you're becoming impatient / need to go / it's getting late. A lot of people actually still wear watches, but by and large, the reason has changed - it's mostly about fashion. For some people, maybe it was always about looks, but now more than ever the watch is, in any functional sense, obsolete.